I have found that I suck at traditional forms of exercise. I feel stupid doing those exercise videos (tried Tae Bo once in college with my roommates and sucked at it and I've tried some others, but never stuck with them because I get irritated and unmotivated if I can't do it exactly right/like the instructors). Stationary bikes are boring, as are treadmills. Sit ups, push ups and all those...yeah, could never do very many, even though I used to be able to pick up a 50# bag of dog food on either shoulder and carry it from outside the vet clinic I worked at into our feed room without really breaking a sweat.
I have to be doing something outdoors and not really considered "exercise" in order to stick with it. So, I get out and hike. The great thing about hiking, is that no one cares what you look like or how much you weigh or anything like that. Heck, most of the time you're out there, you don't see anyone else anyway. And, depending on where you live, you can find some beautiful areas to hike in.
My friend and I were out exploring one day in my (four-wheel-drive) truck and followed some signs to this place: The Upper Verde River. Beautiful setting, varied terrain (great for working different muscle groups), and not another soul in sight.
We did that hike and another one we found while trying to get to a different landmark we used to hike at in high school (called Saddlehorn...it's a small butte that looks like a saddlehorn...turns out it's private property now...epic fail) several times that summer and I lost a good 15lbs or so (lost fat, gained muscle, especially in my legs).